Naturally occurring oils are made of triacylglycerols (TAGs) that account for more than 98% of the total oil. Therefore, the chemical and physical properties of the oils are determined by their triacylglyceride composition and the fatty acid distribution on these molecules.
Vegetable fats and oils used for food and other, non-food applications, where high oxidation stability is needed, require a special triacylglyceride composition, mainly if chemical treatments such as hydrogenation are to be avoided. Partially hydrogenated oils contain trans isomers of fatty acids that are considered undesirable from a nutritional point of view.
Some commodity oils meet part of these requirements but have technological or nutritional disadvantages. For example, palm oil and palm olein have high stability but they are solid or semi-solid at room temperature due to the disaturated and trisaturated TAG content, and nutritionally unhealthy mainly due to the palmitic acid content in the sn-2 TAG position (Renaud et al., J. Nutr. 125:229-237 (1995)). High oleic vegetable oils are liquid to temperatures below 0° C. but are not sufficiently stable. Therefore, uses where stable and liquid oil is required could not be fulfilled with these oils.
Healthy oils with good oxidative stability should have a low content of saturated fatty acids, comprising preferably stearate because it is neutral in respect to the serum cholesterol levels (Pearson, Am. J. Clin. Nutr., 60(S):1071S-1072S, (1994); Kelly et al., Eur. J. of Clinical Nutr., 55:88-96, (2001)), and should not have saturated fatty acids in the middle position (sn-2) of the triacylglyceride. Oils with saturated fatty acids in the middle position of the triacylglyceride have been suggested to be responsible for the atherogenic effects of these oils (Renaud et al., J. Nutr. 125:229-237 (1995)).
WO0019832 teaches how a high-stearate and high-oleate oil from Brassica could be obtained. In addition, some fractions of stearin and olein were obtained.
WO99057990 teaches furthermore how a high-stearate and high-oleate oil from soybean could be obtained and how, in addition, some stearin and olein fractions were obtained. All the oils and fractions shown in these patent publications have more than 0.5% of linolenate Therefore, none of these previous oils or their fractions are a good material to obtain the olein fraction of the present invention.
Some tropical olein fractions blended with standard commodity oils have been proposed to be used as frying fats. As taught in WO2006/061100, an olein fraction from tropical shea butter could be blended with commodity oils resulting in a frying fat. However, shea butter has the disadvantage that it is rather rare, obtained from a tropical trees. For oil manufacture on an industrial scale sourcing may become a problem.
EP-1290119 describes the use of a high stearic high oleic sunflower oil (HSHOSF) for the production of stearin, which is blended with a liquid vegetable oil to prepare a fat phase. The solids content of the stearin fraction is more than 50 wt. % and it contains at least 30 wt. % SUS fatty acids. The stearin fraction is entended for structuring the vegetable oil to obtain a margarin or spread. The stearin fraction thus provides the solids in these products and is not itself a liquid.
Oils made mainly of saturated and monounsaturated fatty acids have very good stability, but, taking into account the TAG biosynthesis in plants, oils with increased saturated fatty acids content will have noticeable amounts of TAGs with two or three saturated fatty acids. These TAGs will precipitate, even at room temperature, making this oils solidify very easily. Oils liquid as low as 0° C. and stable are of industrial interest. Sunflower oils with high-stearate in high-oleate background have very good oxidative stability but are easily solid. Fractions of this oil without most of the disaturated TAGs should have good stability and will be liquid at a temperature of around 0° C.
It is therefore the object of the present invention to provide a new oil that is both liquid at low temperatures and resistant to oxidation.